Individuals with inadequate social support are at greater risk for both cardiovascular and all-cause mortality. One mechanism of action of social support may be through cardiovascular reactivity. Studies have shown that when subjects are provided with support during a stressful laboratory task, by the presence of a friend or a supportive confederate, cardiovascular reactivity to the task is reduced compared to a no-support condition. Most studies of this sort have provided emotional support, that is, feelings of love or encouragement. Another important form of support is instrumental support, feeling that someone will help you should you need it. The present study will test the effects of instrumental support on cardiovascular reactivity by exposing the subject to a confederate who is either helpful (instrumental support), neutral, or competitive. Then the subject will perform a stressful mental arithmetic task in the presence of this confederate. If instrumental support is effective in reducing cardiovascular reactivity to stress, the subjects who performed the task in the presence of the helpful confederate will have reduced cardiovascular reactivity to the task compared to the other two conditions.